This invention relates to the preparation of propellants and explosive charges having high specific impulse and high detonation velocities. More particularly, it relates to the utilization of secondary high explosives such as Beta-HMX and RDX which are physically similar in that they exist only in pulverulent form and chemically similar in that they have pendant nitro groups as part of their molecular configuration. While it should be understood that this invention relates broadly to these types of secondary high explosives, the invention is discussed with particular reference to Beta-HMX (cyclotetramethylenetetranitramine) because of its high density and superior detonation velocity and pressure, although it is not intended that the invention should be so limited.
Beta-HMX is a known secondary high explosive having a high density, high specific impulse and high detonation velocity. While its relatively high cost, as compared, for example, to TNT, has limited the uses to which it has been applied, it has assumed considerable importance in the space program where the release of high bursts of energy are required. The need for such a propellant will become even greater as the space quest moves toward planets such as Venus and Jupiter which, due to their dense atmospheres that are several orders of magnitude greater than Earth's, require the development of substantial kinetic energy in order to effect course corrections, the powering of retro rockets, and the like.
While HMX is one of the better detonating propellants, it suffers from the fact that it can only be made in pulverulent form and cannot be melted and cast, as can TNT, into a compact, coherent mass or charge. To solve this problem, the use of numerous binders has been proposed to secure the HMX particles in a matrix of the binder. The binding materials known to the prior art are deficient in that they may limit the density to which the HMX can be compacted and, by so doing, observably reduce the specific impulse and detonation velocity. In order to minimize this problem, binders comprised of other energetic explosive materials, such as nitrocellulose, have been tested, but even these cause a measurable diminution in the specific impulse and detonation velocity of the HMX.